Natural polysaccharides are high molecular compounds synthesized by organisms and covalently linked by several monosaccharides through glycosidic bonds.They come from a wide range of sources and are found in plants,animals and microbes.Natural polysaccharides contain a variety of biological activities,especially anti-tumor effects.Compared with currently available oncology therapeutic drugs,natural polysaccharides have become one of the research hotspots in the field of anti-tumor due to their safety and high efficiency.Tumor metastasis is the decisive factor of tumor deterioration.Therefore,a thorough understanding of the mechanism of natural polysaccharide anti-tumor metastasis is critical.In this paper,we consulted the literature in recent years to review the mechanism of natural polysaccharides anti-tumor metastasis,in order to provide new reference for the development of anti-tumor metastasis drugs and the clinical application of natural polysaccharides.